U.S. patent application number 10/314831 was filed with the patent office on 2003-07-03 for polymers modified by functional groups.
Invention is credited to Braubach, Wilfried, Grun, Michael.
Application Number | 20030125476 10/314831 |
Document ID | / |
Family ID | 7708817 |
Filed Date | 2003-07-03 |
United States Patent
Application |
20030125476 |
Kind Code |
A1 |
Grun, Michael ; et
al. |
July 3, 2003 |
Polymers modified by functional groups
Abstract
The present invention relates to polymers which are modified by
functional end groups and are based on conjugated dienes or on
conjugated dienes and vinylaromatic compounds, a process for their
preparation and their use for the production of rubber shaped
articles of all types, in particular for the production of tires
and tire components, such as tire treads.
Inventors: |
Grun, Michael; (Siegburg,
DE) ; Braubach, Wilfried; (Solingen, DE) |
Correspondence
Address: |
BAYER POLYMERS LLC
100 BAYER ROAD
PITTSBURGH
PA
15205
US
|
Family ID: |
7708817 |
Appl. No.: |
10/314831 |
Filed: |
December 9, 2002 |
Current U.S.
Class: |
525/332.9 ;
525/374 |
Current CPC
Class: |
C08C 19/44 20130101;
C08F 8/30 20130101; C08F 8/42 20130101 |
Class at
Publication: |
525/332.9 ;
525/374 |
International
Class: |
C08F 008/30 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2001 |
DE |
10160849.7 |
Claims
What is claimed is:
1. Polymers which are modified by functional end groups and are
based on conjugated dienes or on conjugated dienes and
vinylaromatic compounds, and have an average molecular weight (Mw)
of greater than 10,000 g/mol, a molecular weight distribution
(Mn/Mw) of 1.3 to 5 and have functional end groups which are
derived from compounds of the formula (I) 7wherein R.sup.1 and
R.sup.2 are identical or different and represent hydrogen, or
represent linear or branched alkyl groups having 1 to 15 carbon
atoms, or represent aryl groups having 6 to 10 carbon atoms, or
represent cycloalkyl groups having 5 to 10 carbon atoms, or
represent aralkyl groups having 1 to 4 carbon atoms in the alkyl
part and 6 to 10 carbon atoms in the aryl part, or wherein R.sup.1
and R.sup.2, together with the nitrogen atom, form a heterocyclic
ring which contains 2 to 10 carbon atoms, and in addition can also
be interrupted by 1 to 3 heteroatoms of the third to seventh main
group of the periodic table of the elements, such as nitrogen,
oxygen or sulfur, or from compounds of the formula (II) 8wherein
R.sup.3 to R.sup.7 are identical or different and represent
hydrogen, linear or branched alkyl groups having 1 to 15 carbon
atoms, aryl groups having 6 to 10 carbon atoms, cycloalkyl groups
having 5 to 10 carbon atoms or aralkyl groups having 1 to 4 carbon
atoms in the alkyl part and 6 to 10 carbon atoms in the aryl part,
or wherein R.sup.3 to R.sup.7 represent the radical 9and n, m, o, p
independently of one another represent the numbers 1 to 12, the
content of functional end groups being 40 to 100 mol%, based on the
total number of polymer chains present.
2. A process for the preparation of the modified polymers according
to claim 1, wherein conjugated dienes or conjugated dienes and
vinylaromatic compounds are reacted in an inert organic solvent in
the presence of an alkali metal and/or an alkaline earth metal
catalyst and the anionic polymer terminated by alkali metal and/or
alkaline earth metal is then reacted with at least one of the
compounds of the formula (I) and/or (II) mentioned in claim 1, the
compounds of the formula (I) and/or (II) being employed in amounts
of 0.1 to 10 mol per 1 mol of the initiator employed.
3. Shaped articles comprising the polymers according to claim
1.
4. Shaped articles according to claim 3, wherein said shaped
article is a tire or tire component.
Description
FIELD OF THE INVENTION
[0001] The present invention provides polymers which are modified
by functional end groups and are based on conjugated dienes or on
conjugated dienes and vinylaromatic compounds, a process for their
preparation and their use for the production of rubber shaped
articles of all types, in particular for the production of tires
and tire components, such as tire treads.
BACKGROUND OF THE INVENTION
[0002] It is known, to improve the physical properties of the
rubbers used in tire construction in particular, to modify these in
the most diverse manner, for example by introduction of particular
end groups or by modification of the internal build-up of the
polymer molecules. By modification of the polymers, for example by
introduction of particular end groups, the physical properties, for
example the rolling resistance or the wet skid properties, are said
to be improved, as mentioned, in order to lower the fuel costs of
cars and to increase their safety, in particular in the wet.
Furthermore, bonding of the rubbers to be employed in tire
construction to the fillers used there, in particular to the
light-colored fillers, such as silica, should be improved
substantially, so that a firm bond arises between the rubber matrix
and the filler. The processing of such polymers or rubbers, in
particular those to which light-colored fillers have been added, in
the corresponding processing machines is furthermore said to be
improved by the introduction of particular functional groups into
the polymer molecules. British Patent Application GB 2 117 778-A
and European Patent Application 0 180 853 A describe methods for
the modification of unsaturated polymers with, for example,
aromatic ketones or particular aminoaldehydes or aminoketones. By
introduction of appropriate end groups into the unsaturated
polymers, a good balance between rolling resistance and wet skid
resistance in the tire rubber is achieved.
[0003] European Patent Application EP 0 767 179 A2 describes a
process for the preparation of rubber mixtures which are modified
in the end group by particular organosilicon compounds. A better
bonding of the rubbers to the fillers comprising silica is said to
be effected by the end group modification of the corresponding
rubbers.
[0004] As has been found in our own experiments, the organosilicon
compounds described in the European Patent Application mentioned,
which are said to be for modification of the rubbers, are not so
stable that they could withstand an attack by polymer anions. This
means that the organosilicon compounds employed according to the
European Patent Application for the modification of the rubbers
lead not only to an end group modification of the rubbers but also
to a high degree to undesirable multiple coupling reactions of the
polymer anions present.
SUMMARY OF THE INVENTION
[0005] The object of the present invention is to provide polymers
which are modified by functional end groups and are based on
conjugated dienes or on conjugated dienes and vinylaromatic
compounds, and which show, in particular, improvements in respect
of the processing properties together with improved physical and
dynamic properties and therefore, bring about a more balanced ratio
of wet skid resistance and rolling resistance in the tire
rubbers.
DETAILED DESCRIPTION OF THE INVENTION
[0006] Therefore, the present invention provides polymers which are
modified by functional end groups and are based on conjugated
dienes or on conjugated dienes and vinylaromatic compounds, and
have an average molecular weight (M.sub.w) of greater than 10,000
g/mol, a molecular weight distribution (M.sub.n/M.sub.w) of 1.3 to
5 and have functional end groups which are derived from compounds
of the formula (I) 1
[0007] wherein
[0008] R.sup.1 and R.sup.2 are identical or different and represent
hydrogen, or represent linear or branched alkyl groups having 1 to
15 carbon atoms, or represent aryl groups having 6 to 10 carbon
atoms, or represent cycloalkyl groups having 5 to 10 carbon atoms,
or represent aralkyl groups having 1 to 4 carbon atoms in the alkyl
part and 6 to 10 carbon atoms in the aryl part, or wherein
[0009] R.sup.1 and R.sup.2, together with the nitrogen atom, form a
heterocyclic ring which contains 2 to 10 carbon atoms, and in
addition can also be interrupted by 1 to 3 heteroatoms of the third
to seventh main group of the periodic table of the elements, such
as nitrogen, oxygen or sulfur,
[0010] or from compounds of the formula (II) 2
[0011] wherein
[0012] R.sup.3 to R.sup.7 are identical or different and represent
hydrogen, linear or branched alkyl groups having 1 to 15 carbon
atoms, aryl groups having 6 to 10 carbon atoms, cycloalkyl groups
having 5 to 10 carbon atoms or aralkyl groups having 1 to 4 carbon
atoms in the alkyl part and 6 to 10 carbon atoms in the aryl part,
or
[0013] wherein
[0014] R.sup.3 to R.sup.7 represent the radical 3
[0015] and
[0016] n, m, o, p independently of one another represent the
numbers 1 to 12, the content of functional end groups being 40 to
100 mol %, based on the total number of polymer chains present.
[0017] The polymers according to the invention preferably have an
average molecular weight (M.sub.w) of 1,000 to 2,000,000,
preferably 100,000 to 800,000.
[0018] The molecular weight distribution (M.sub.n/M.sub.w) is
preferably in a range from 1.3 to 4, preferably in the range from
1.5 to 3.5.
[0019] The polymers modified according to the present invention
have, in particular, a content of functional end groups of 50 to
100 mol %, preferably 70 to 100 mol %.
[0020] The modified polymers according to the present invention
have--depending on the nature of the modifying agents employed, the
reaction conditions which exist and the chosen molar ratios of the
modifying agents employed to the polymerizable monomers--a degree
of coupling of about 10 to 20%, preferably 12 to 17%, based on the
total number of polymer chains present. The degree of coupling is
caused by a linear coupling reaction of the modifying agents
employed with the polymer anions present, which contributes towards
a molecular weight coupling.
[0021] The T.sub.g value of the modified polymers according to the
present invention is -10 to -50.degree. C., preferably -15 to
-30.degree. C.
[0022] All known dienes which are conventional for the preparation
of appropriate polymer anions can be employed as conjugated dienes
for building up the polymers according to the present invention.
Examples which may be mentioned are: 1,3-butadiene,
2,3-dimethyl-1,3-butadiene, 3-butyl-1,3-octadiene, isoprene,
piperylene, 1,3-hexadiene, 1,3-octadiene and
2-phenyl-1,3-butadiene, preferably 1,3-butadiene and isoprene and
mixtures thereof.
[0023] Possible vinylaromatic compounds are likewise the known
vinylaromatic compounds which can be copolymerized together with
the conjugated dienes. Examples which are to be mentioned are:
styrene, p-methylstyrene, .alpha.-methylstyrene,
3,5-dimethylstyrene, vinylnaphthalene, p-tert-butylstyrene,
divinylstyrene, divinylethylene, 4-propyistyrene, p-tolylstyrene, 1
-vinyl-5-hexylnaphthalene, 1-vinylnaphthalene or mixtures of the
vinylaromatic compounds mentioned, preferably styrene,
p-methylstyrene and .alpha.-methylstyrene, in particular
styrene.
[0024] In the copolymers, the content of vinylaromatic compounds is
conventionally 5 to 55 wt. %, preferably 10 to 45 wt. %, and the
amount of conjugated dienes is correspondingly 45 to 95 wt. %,
preferably 55 to 90 wt. %. The copolymers can be a random, staged
block or complete block copolymer of the various monomers
mentioned.
[0025] Radicals R.sup.1 and R.sup.2 in the abovementioned formula
(I) which are to be mentioned as preferred are: hydrogen, linear or
branched alkyl radicals having 1 to 6 carbon atoms, such as methyl,
ethyl, propyl, butyl, pentyl, isopropyl, isobutyl and isopentyl,
aryl radicals having 6 to 10 carbon atoms, such as phenyl, naphthyl
and xylyl, alkylaryl radicals having 1 to 4 carbon atoms in the
alkyl part and 6 to 10 carbon atoms in the aryl part, such as
methyl, ethyl, propyl, butyl, pentyl, isopropyl, isobutyl and
isopentyl in the alkyl part and phenyl, naphthyl and xylyl in the
aryl part, and radicals wherein R.sup.1 and R.sup.2, together with
nitrogen, form a heterocyclic ring which contains 2 to 10 carbon
atoms and is additionally interrupted once by oxygen, nitrogen or
sulfur, in particular by oxygen, and cycloalkyl groups having 5 to
7 carbon atoms, such as cyclopentyl and cyclohexyl. Particularly
preferred suitable radicals R.sup.1 and R.sup.2 in the formula (I)
are: methyl, ethyl, isopropyl, phenyl, cyclohexyl and isobutyl, and
radicals wherein R.sup.1 and R.sup.2, together with the nitrogen,
in the formula (I) form a heterocyclic ring, such as a morpholine,
1-pyrrolidine or 2,3-dioxo-4-ethyl-1-piperazine ring.
[0026] The compounds of the formula (I) can of course be
substituted, in particular mono- or disubstituted, by alkyl
radicals having 1 to 4 carbon atoms, such as methyl, ethyl, propyl
and isopropyl.
[0027] The compounds of the formula (I) listed by way of formulae
below are preferably used for modification of the polymers: 4
[0028] Possible preferred radicals R.sup.3 to R.sup.7 in the
formula (II) are the radicals R.sup.1 and R.sup.2 already mentioned
as preferred for the formula (I). In addition, the epoxy-ether
radical already mentioned in the formula (II) is preferred.
Preferred numbers for n, m, o and p in the formula (II) are 1 to
10.
[0029] The alkyl radicals are very preferred as radicals R.sup.3 to
R.sup.7 in the formula (II), such as the methyl, ethyl, propyl,
isopropyl, butyl, isobutyl and the pentyl and isopentyl
radical.
[0030] Compounds of the formula (II) in which the radical R.sup.7
represents the epoxy-ether radical described in more detail above
are likewise very particularly preferred.
[0031] The preferred epoxy-silyl ethers of the formula (II) are
listed below by way of their formulae: 5 6
[0032] It is of course possible to employ the compounds of the
formula (I) and (II) in any desired mixture with one another in the
modification of the polymers, so that polymers with corresponding
mixed functional end groups are formed.
[0033] The present invention also provides a process for the
preparation of polymers which are modified by functional end groups
and are based on conjugated dienes or on conjugated dienes and
vinylaromatic compounds and have the above-mentioned average
molecular weight, the molecular weight distribution mentioned and
the content mentioned of functional end groups, which is
characterized in that conjugated dienes or conjugated dienes and
vinylaromatic compounds are reacted in an inert organic solvent in
the presence of an alkali metal and/or alkaline earth metal
catalyst and the anionic polymer terminated by alkali metal and/or
alkaline earth metal is then reacted with at least one of the
abovementioned compounds of the formula (I) and/or (II), the
compounds of the formula (I) and/or (II) being employed in amounts
of 0.1 to 10 mol per 1 mol of the initiator employed.
[0034] The polymerization of the conjugated dienes or of the
conjugated dienes with the vinylaromatic compounds
(copolymerization) takes place in an inert, aprotic, organic
solvent, such as, for example, paraffinic hydrocarbons, e.g.
isomeric pentanes, hexanes, heptanes, octanes or decanes,
2,4-trimethylpentane, cyclopentane, cyclohexane, methylcyclohexane,
ethylcyclohexane or 1,4-dimethylcyclohexane, or aromatic
hydrocarbons, such as benzene, toluene, ethylbenzene, xylene,
dimethylbenzene or propylbenzene. These solvents can be employed
individually or as a mixture with one another. Cyclohexane and
n-hexane are preferably employed as the solvent.
[0035] A polar solvent can optionally be added to the aprotic
solvents mentioned in the copolymerization of vinylaromatic
compounds with the conjugated dienes to increase the rate of
polymerization and/or for modification of the polymer structures.
Suitable polar solvents include ethers, such as tetrahydrofuran,
diethyl ether, cycloallyl ether, dipropyl ether, ethylene-dimethyl
ether, ethylene-diethyl ether, diethylene glycol, dimethyl ether,
tert-butoxyethoxyethane or bis-(2-dimethylaminoethyl)ether,
preferably tert-butoxyethoxyethane or
bis-(2-dimethylaminoethyl)ether, and tertiary amines, such as
trimethylamine, triethylamine tripropylamine or
tetramethylethylenediamin- e, preferably triethylamine or
tetramethylethylenediamine. The microstructure of the corresponding
copolymers can, furthermore, be modified with the addition of the
polar solvent, for example from staged block to random. The polar
solvents to be employed for modification of the polymers are in
general employed in the anionic polymerization in amounts of 0.1 to
40 mol, preferably 0.1 to 10 mol per 1 mol of the alkali metal or
alkaline earth metal catalyst employed.
[0036] The amount of solvent to be employed can vary within wide
ranges. It is conventionally about 300 to 1,500 parts by wt. per
part by wt. of total monomers.
[0037] The preparation of the polymers modified according to the
present invention is carried out in two steps. In the first step, a
live, anionic polymer which is terminated by alkali metal or
alkaline earth metal is prepared, and in the second step is linked
in the end group with the compounds of the formula (I) and (II)
according to the invention defined above.
[0038] The first step of the preparation of the polymers according
to the present invention is in general carried out by a procedure
in which, preferably, an alkali metal initiator system is reacted
with the particular monomer or the monomer mixture in order to form
the live anionic polymers. This polymerization step can be carried
out in one step or in a sequence of steps. If the polymeric chain
is a homopolymer or a random or staged copolymer of two or more
monomers, the monomers are polymerized simultaneously with the
alkali metal catalyst. If the polymer chain is a block copolymer
which comprises two or more homo- or copolymer blocks, the
individual blocks can be produced in incremental or successive
additions of monomer.
[0039] Alkali metal or alkaline earth metal catalysts which can be
employed are lithium, sodium, potassium, rubidium, cesium,
beryllium, magnesium, calcium, strontium and barium, and lithium is
preferably employed.
[0040] Furthermore, the alkali metal compounds of the general
formula
R.sup.1-M
[0041] wherein
[0042] R.sup.1 represents a hydrocarbonyl radical having 1 to 20
carbon atoms and
[0043] M is an alkali metal chosen from lithium, sodium, potassium,
rubidium or cesium
[0044] are preferably employed as the alkali metal-based initiator
systems (catalyst systems).
[0045] Examples of such initiator systems are methyllithium,
isopropyllithium, n-butyllithium, s-butyllithium, isobutyllithium,
tert-butyllithium, tert-octyllithium, hexyllithium,
n-undecyllithium, phenyllithium, naphthyllithium, p-tolyllithium,
4-phenylbutyllithium, cyclohexyllithium and
4-cyclohexylbutyllithium.
[0046] The amount of alkali metals, alkaline earth metals or alkali
metal compounds to be employed depends on the desired properties of
the polymer, in particular the desired molecular weight. The alkali
metal compounds are usually employed in the range from 0.2 to 20
mmol/100 g of the monomers employed in total.
[0047] The polymerization temperature can vary within wide ranges
and is in general in the range from 0.degree. C. to 200.degree. C.,
and is preferably 40.degree. C. to 130.degree. C. The reaction time
likewise varies within wide ranges from a few minutes up to some
hours. The polymerization is conventionally carried out within a
time span of about 30 minutes to 8 hours, preferably 4 hours. It
can be carried out both under normal pressure and under increased
pressure (up to 10 bar).
[0048] In carrying out the second reaction step, the anionic
polymers obtained, which are terminated by alkali metal and/or
alkaline earth metal, are reacted with at least one of the
compounds of the formula (I) and (II) mentioned, i.e. the modifying
agents, the compounds of the formula (I) and (II) preferably being
employed in amounts of 0.5 to 4 mol per 1 mol of the initiator
employed.
[0049] In this so-called end group modification, it is to be
ensured that interfering compounds which can impair the end group
modification are not present. Such interfering compounds are e.g.
carbon dioxide, oxygen, water, halides, alcohols and organic and
inorganic acids and other protic organic substances.
[0050] The linking reaction (i.e. the modification reaction) is
conventionally carried out at temperatures which approximately
correspond to the temperatures of the polymerization reaction. This
means that the linking reaction is carried out at temperatures from
about 0.degree. C. to 200.degree. C., preferably 50.degree. C. to
120.degree. C. The linking reaction can likewise be carried out
under normal pressure and also under increased pressure (1 bar to
10 bar).
[0051] The linking reaction is relatively short. It is in the range
from about 1 minute to 1 hour.
[0052] After the linking reaction, the polymers modified in the end
group which now result are obtained by treating the reaction
mixture with terminating reagents which contain active hydrogen.
Such terminating reagents are, for example, alcohols or water or
mixtures thereof. It is furthermore of advantage if antioxidants
are added to the reaction mixture before the linked polymer is
isolated.
[0053] The polymer according to the present invention is separated
off in the conventional manner, for example by steam distillation
or flocculation with a suitable flocculating agent, such as
alcohol. The polymer which has been flocculated out is then removed
from the resulting medium, for example, by centrifugation or
extrusion. Residual solvent and other volatile constituents can be
removed from the isolated polymer by heating, optionally under
reduced pressure or in a fan-assisted air stream.
[0054] The polymers according to the present invention can be
prepared both in a discontinuous and in a continuous procedure. The
continuous procedure in a reaction cascade comprising several,
preferably at least two, in particular 2 to 4, reactors connected
in series is preferred.
[0055] As already mentioned above, during the linking of the
polymer anions with the modifying agents described, coupled
polymers are also obtained to a certain degree (about 10 to 20%,
based on the total number of polymer chains present), the degree of
coupling of which--as likewise explained above--depends on the
modifying agents employed, on the molar ratios chosen between the
modifying agents and monomers and on the reaction conditions
chosen.
[0056] The conventional compounding components, such as fillers,
dyestuffs, pigments, softening agents and reinforcing agents, can
of course also be added to the polymers according to the present
invention; furthermore the known rubber auxiliaries and
crosslinking agents as described in "Handbuch fur die
Gummiindustrie [Handbook for the Rubber Industry]", 2nd edition,
1991, publisher: Bayer A G.
[0057] The polymers according to the invention which are modified
by functional end groups can be used in a known manner for the
production of rubber shaped articles of all types, in particular
for the production of tires and tire components, of golf balls and
other industrial rubber articles, and also for the production of
rubber-reinforced plastics, such as ABS and HIPS plastics.
[0058] It is furthermore possible to blend the polymers according
to the present invention which are modified by functional end
groups with other rubbers, such as natural rubber or other
synthetic rubbers, such as polybutadiene and SBR, in order to
achieve the most favorable physical properties of the rubber shaped
articles--according to the intended use.
[0059] The most favorable mixing ratio can easily be determined
here according to the aim of use by means of preliminary
experiments. The non-modified rubbers mentioned are conventionally
added in amounts of about 1 to 50 parts by weight per 100 parts by
weight of the total rubber mixture.
[0060] It is, of course, also possible to blend the polymers
modified in the manner according to the present invention with
other known polymers modified in the end group, the known polymers
modified in the end group being employed in amounts of about 1 to
50, preferably 5 to 45 parts by wt. per 100 parts by wt. of the
total rubber mixture. Other polymers modified in the end group are
known, for example, from Houben-Weyl; Methoden der organischen
Chemie [Methods of Organic Chemistry]; 4th edition volume E20,
Makromolekulare Stoffe [Macromolecular Substances], p. 129 et seq.
and 1994 et seq.; Georg-Thieme Verlag Stuttgart-N.Y. 1986. The end
group can be modified here by reaction of the polymer anions with
alcohols, aldehydes, ketones, amines, organotin compounds or
isocyanates.
EXAMPLES
Example 1
[0061] Preparation of a styrene/butadiene copolymer with modified
end groups, with N,N'-dimethylcarbamic acid chloride as the
modifying agent.
[0062] 8,500 g technical-grade hexane were initially introduced
into an autoclave which was purged with nitrogen and provided with
a stirrer. Thereafter, 49.90 mmol tert-butoxy-ethoxyethane, 0.94
mmol potassium tert-amylate and 17 mmol n-butyllithium (BuLi) were
added, while stirring, to the hexane which had been initially
introduced. 1,200 g dried, destabilized 1,3-butadiene and 345 g
dried, destabilized styrene were then metered into this mixture.
The polymerization of the monomers was carried out at a temperature
of 70.degree. C. until conversion of the monomer was complete. 17
mmol N,N'-dimethylcarbamic acid chloride were then metered into the
mixture in situ and the mixture was subsequently stirred for 30 min
at 70.degree. C. Thereafter, the contents of the reactor were
cooled and the reaction was stopped with ethanol. The product
obtained was then stabilized with Vulkanox.RTM. BHT and dried at
60.degree. C. in a drying cabinet.
Example 2
[0063] Preparation of a styrene/butadiene copolymer with modified
end groups, with
1,3-bis-(3-glycidyloxypropyl)-tetramethyldisiloxane as the
modifying agent.
[0064] 8,500 g technical-grade hexane were initially introduced
into an autoclave which was purged with nitrogen and provided with
a stirrer. Thereafter, 49.90 mmol tert-butoxy-ethoxyethane, 0.94
mmol potassium tert-amylate and 17 mmol n-butyllithium (BuLi) were
added, while stirring, to the hexane which had been initially
introduced. 1,200 9 dried, destabilized 1,3-butadiene and 345 g
dried, destabilized styrene were then metered into this mixture.
The polymerization of the monomers was carried out at a temperature
of 70.degree. C. until conversion of the monomer was complete. 17
mmol 1,3-bis-(3-glycidyloxypropyl)-tetramethyldi- siloxane were
then metered into the mixture in situ and the mixture was
subsequently stirred for 30 min at 70.degree. C. Thereafter, the
contents of the reactor were cooled and the reaction was stopped
with ethanol. The product obtained was then stabilized with
Vulkanox.RTM. BHT and dried at 60.degree. C. in a drying
cabinet.
[0065] The physical parameters of the copolymer obtained are listed
in the following table.
1TABLE 1 Polymer analysis of the modified polymers obtained gave
the following data: ML1 + 4 GPC @ 100.degree. Styrene 1,4-cis
1,4-trans Vinyl T.sub.g L value before L value after M.sub.w
Polydis- C. [wt. %] [wt.%] [wt. %] [wt. %] [.degree. C.]
modification modification [g/mol] persion Example 1 57 19.8 12.1
16.2 52.0 -23.5 212 248 333,390 1.5 Example 2 60 19.3 12.2 16.2
52.4 -24.2 196 249 362,029 1.6 Reference 58 19.3 12.5 16.9 51.3
-24.2 191 191 305,705 1.3 GPC Elemental Coupling yield
M.sub.w[g/mol] Polydispersion analysis according to GPC Example 1
333,390 1.5 152 ppm (N) 20% Example 2 362,029 1.6 220 ppm (Si) 34%
ML 1 + 4: Mooney values GPC: Gel permeation chromatography M.sub.w:
average molecular weight, 1 Polydispersion = M w M n EINBETTENL
value: Viscosity number (0.5 g polymer/100 ml toluene) 2 Evaluation
according to : L = ( t t 0 - 1 ) 200 EINBETTENwhere t = flow time
of the polymer solution in sec t.sub.0 = flow time of the solvent
in sec Microstructure determined by infrared spectroscopy T.sub.g:
Glass transition temperature according to DSC (differential
scanning calorimetry) Reference: Styrene/butadiene copolymer
without end group functionalization prepared analogously to the
recipe of example 1.
[0066] The properties of vulcanization products with carbon black
as a filler and silica as a filler with polymers according to the
invention and polymers which were only coupled but not modified in
end groups (not according to the invention) are listed in the
following tables.
2TABLE 2 Carbon black mixtures Reference Example 1 Example 2
Reference according to the prior art 60 Polymer example 1 60
Polymer example 2 60 Buna CB 25 .RTM. 40 40 40 Carbon Black N 234
50 50 50 Mineral oil* 5 5 5 ZnO RS 3 3 3 Stearic acid 2 2 2 Antilux
654 .RTM.** 1.5 1.5 1.5 Vulkanox HS .RTM.**** 1 1 1 Vulkanox 4020
.RTM.*** 1 1 1 Vulkacit CZ .RTM.****** 1.4 1.4 1.4 Vulkacit D
.RTM.******* 0.3 0.3 0.3 Sulfur 1.8 1.8 1.8
[0067]
3TABLE 3 Mixture properties, DIN 53523 Mooney viscosity 81 79 81
ML1 + 4 @ 100.degree. C. Vulcanization product properties, ISO 37
Strength, MPa 21.08 20.328 19.35 Elongation at break, % 392 386 378
Modulus 100%, MPa 2.88 2.63 2.85 Modulus 300%, MPa 13.76 14.38
14.07 Degree of reinforcement 4.8 5.5 4.9 Hardness 23.degree. C.,
Shore A 65.7 63.9 64.6 Hardness 70.degree. C., Shore A 64 63 62.8
Elasticity 23.degree. C., % 48 45.8 47.8 Elasticity 70.degree. C.,
% 58.7 60.4 59.8 Roelig, 10 HZ, DIN 53513 tan delta 60.degree. C.
0.129 1.122 0.123
[0068] In typical vulcanization products with carbon black as a
filler for tire treads, the polymers according to the invention
called example 1 and example 2 show significant advantages in the
degree of reinforcement compared with the polymer according to the
prior art (reference), which illustrates the interaction of the
polymer with the filler. As a consequence, this leads to an
increase in the elasticity, especially at high temperatures
(70.degree. C.), and to a lowering of the Roelig tan delta at
60.degree. C., which the expert equates with a reduction in the
rolling resistance of correspondingly produced tires.
4TABLE 4 Silica mixtures Reference Example 1 Example 2 Reference
according to the prior 70 art (coupled) Polymer example 1 70
Polymer example 2 70 Buna CB 25 .RTM. 30 30 30 Mineral oil* 37.5
37.5 37.5 Vulkasil S .RTM.******** 80 80 80 Silane Si 69
.RTM.********* 6.4 6.4 6.4 ZnO RS 2.5 2.5 2.5 Stearic acid 1 1 1
Vulkanox HS .RTM.**** 1 1 1 Vulkanox 4020 .RTM.*** 1 1 1 Vulkacit
CZ .RTM.****** 1.8 1.8 1.8 Vulkacit D .RTM.******* 2 2 2 Sulfur 1.5
1.5 1.5
[0069]
5TABLE 5 Mixture properties, DIN 53523 Mooney viscosity 80.5 80.5
83.0 ML1 + 4 @ 100.degree. C. Vulcanization product properties, ISO
37 Strength, MPa 16.8 18.3 18.5 Elongation at break, % 393 425 422
Modulus 100%, MPa 3.6 3.1 3.4 Modulus 300%, MPa 11.8 11.7 11.5
Degree of reinforcement 3.3 3.8 3.4 Hardness 23.degree. C., Shore A
73 72 72 Hardness 70.degree. C., Shore A 71 71 71 Elasticity
23.degree. C., % 37 39 41 Elasticity 70.degree. C., % 55 56 58
Roelig, 10 HZ, DIN 53513 tan delta -20.degree. C. 0.389 0.433 0.420
60 0.121 0.115 0.115 *Enerthene 1849-1, mineral oil plasticizer,
Mobil Schmierstoff GmbH **Light stabilizer wax, Rhein Chemie
Rheinau ***Anti-aging agent (6PPD), Bayer AG ****Anti-aging agent
(TMQ), Bayer AG ******Sulfenamide accelerator (CBS), Bayer AG
*******Guanidine accelerator (DPG), Bayer AG ********Silica, Bayer
AG *********Silane, Degussa
[0070] In vulcanization products with silica as the filler, the
polymers according to the invention likewise show an improved
interaction with the filler, expressed by increased degrees of
reinforcement. In addition to the reduced rolling resistance (lower
tan delta at 60.degree. C.), with this type of tread mixtures the
properties in the wet of tires produced therefrom are improved
(increased tan delta at -20.degree. C.).
[0071] Although the invention has been described in detail in the
foregoing for the purpose of illustration, it is to be understood
that such detail is solely for that purpose and that variations can
be made therein by those skilled in the art without departing from
the spirit and scope of the invention except as it may be limited
by the claims.
* * * * *